The World Trade Center Health Registry (WTCHR), the largest post-disaster exposure health registry in U.S. history, is following a diverse cohort of 71,437 directly affected people who performed 9/11-related rescue/recovery work or lived, worked or attended school in lower Manhattan on 9/11/01. The goals are to identify the long-term physical and mental health effects of the 9/11 WTC disaster;disseminate findings and recommendations to enrollees and others exposed, the public, and the scientific community;share information about 9/11-related resources and services;and inform healthcare policy and disaster response planning. Specific aims are to: 1) Expand knowledge about the long-term health effects of 9/11 by continuing the WTCHR research program;2) Conduct community activities to respond to the physical and mental health concerns and specific healthcare needs of enrollees and others exposed to 9/11;and 3) Maintain the Registry as a valuable public health resource for future research. Aim 1 entails conducting priority epidemiological analyses using data from the baseline (2003-04) and follow-up (2006-08) surveys, including analyses to assess risk factors for the development or persistence of serious respiratory and mental health conditions over time;developing and conducting a second follow-up survey of all enrollees using multiple survey modes (paper, web and telephone) to ascertain the health status and 9/11-related healthcare needs of the cohort ~10 years after 9/11; matching with vital records, cancer registries, and the national death certificate system for cancer and mortality assessments;and investigating other potential emerging health conditions through public health surveillance, medical record review and follow-up case-control studies. The WTCHR will also facilitate independent and collaborative 9/11-related research by providing qualified external researchers with de-identified data and access to enrollee subgroups for re